Mitsubishi Electric MDS-D-SPJ3 Specification Manual page 185

MITSUBISHI CNC
7 Selection
(c) Approximation when using the NC command linear acceleration/deceleration pattern + servo SHG
control (option)
This is a servo's position control method to achieve a normal command pattern and high precision. SHG
control improves the position loop gain by stably controlling a delay of the position loop in the servo
system. This allows the settling time to be reduced and a high precision to be achieved.
Using the expression (7-5) and (7-6), approximate the maximum torque "Ta1" and maximum torque
occurrence speed "Nm" required for this acceleration/deceleration pattern.
T 1 =
a
1000
Nm =N {1-
1.3 Kp ta
N
J
J
η
T
T
Motor speed
r/min NC command
N
Nm
0
Motor
acceleration
Ac
0
Fig.2 Speed, acceleration and torque characteristics when using the NC command linear
7 - 6
(1- 0.586
ta
-2 Kp ta
(1-1.5 e )}
1000
: Motor reach speed
: Motor shaft conversion load inertia
L
: Motor inertia
M
: Drive system efficiency (Normally 0.8 to 0.95)
: Maximum motor torque
MAX
: Motor shaft conversion load (friction, unbalance) torque
L
Motor actual speed
ta
Time (ms)
Motor acceleration
ta
Time (ms)
acceleration/deceleration pattern + servo SHG control
-2 Kp ta
.
e )+T (N m)
••• (7-5)
1000
L
(r/min)
••• (7-6)
Motor
torque
Ta 1
TL
0
(r/min)
2
(kg•cm )
2
(kg•cm )
(N•m)
(N•m)
Speed most required
for the motor torque
Nm N
Motor speed
(r/min)